The invention relates to a switch for controlling door locks, which door locks comprise a non-rotatable locking cylinder case and a lock cylinder which can be rotated from outside by an inserted door key, as well as a resetting spring for returning the locking cylinder to the neutral position from the "open" position and to the neutral position from the "closed" position. Such door locks are typical of automobiles, trailers, trucks, and sometimes of motor cycles, front doors of houses, etc.
Door locks e.g. on automobiles comprise a locking cylinder case which is rigidly connected to the door. A locking cylinder is rotatably mounted in the case. A key can be inserted into its slit from the outside. Springs are always active between the case and the locking cylinder. If neither of the springs is tensioned, the locking cylinder occupies its central position. In this position a key can be introduced into the slit of the keyhole. In cases where door locks lock on the righthand side, the key must then be moved in a clockwise direction thereby moving a driver mechanism inside the door which controls the mechanism in the door interior so that the door is closed. The key is then released or actively returned to its neutral position, the driver also being moved into the neutral position. The spring mechanism ensures that the neutral position is reached and also maintained during travel. If it is desired to open the door, the key in a door lock which locks on the right side is turned in an anticlockwise direction after its insertion thus causing the driver, rigidly attached to the locking cylinder, to move anticlockwise and therefore controlling the locking mechanism inside the door so that the door is opened. Then the key is released again or caused to return to the neutral position. This is ensured by a spring mechanism which maintains this position also during travel.
In addition to the door locks which lock on the right side, there are also locks which lock on the left side. One feature common to all locks, however, is the automatic or forced return to the neutral position due to active rotation or the return springs.
The angle through which the key must be turned to open or close the door can vary greatly. With some automobile models it is in the region of .+-. 10.degree. while on other models the key must be rotated even by more than .+-. 100.degree..
There has been a growing trend towards the use of security systems in large numbers intended to prevent the unauthorized use, or even loading of automobiles since break-ins and thefts from automobiles have increased considerably. These systems have one or several of the following disadvantages:
a. They are costly.
b. They must be actuated separately when leaving the car, e.g. by pressing a switch, which can be forgotten.
c. A theft can observe whether security precautions are taken when leaving the car.
d. In practice the systems are only suitable for certain types of cars.
e. The rightful owner cannot cancel the actuated alarm sufficiently quickly himself so that he may be mistaken for a thief by passers-by. An alarm can be activated by mistake e.g. if a further article which has been forgotten is taken from the trunk after the doors are closed and the security system actuated.
f. It is often easy to render the actuating switch inoperative.
g. A special key is required in place of the original key.